1. Field of the Invention
This invention relates to a connector for the interconnection in perpendicular array of generally C-shaped elongate structural members having a pair of flanges integrally and perpendicularly connected with the web portion thereof in which said flanges each include a flange return edge which extends inwardly of the generally C-shaped channel, which connector, upon the assembly of such interconnection, provides strengthening of the webs of each said C-shaped structural member.
2. Description of the Prior Art
Lightweight metal structural framing members, such as steel joists, provide efficient and economical means for the construction of intermediate size buildings. The basic components of lightweight metal structural framing systems are studs, stud tracks or runners and joists, and each component is currently manufactured in a wide assortment of widths, lengths and thicknesses or gauges to meet a broad range of load and functional requirements. To speed enclosure of such intermediate size buildings, the cutting and assembly of components for wall sections can be performed off-site and under sheltered conditions, and complete sections may be then prefabricated for shipment to the job site. However, prefabrication of floor, ceiling and roofing sections off-site for shipment to the field or to the job site is generally neither economically nor logistically possible when those sections are extraordinarily large or heavy, given the size and weight of such pre-assembled sections, which make necessary heavy equipment for the placement of such sections in the field and preclude lifting such pre-assembled sections into place by hand. Assembly in the field thus being necessary for large or heavy floor, ceiling and roof systems comprising light metal framing, ease of assembly in the field becomes critical for human safety, logistic and economic reasons. Up to the present time, joists and other generally horizontal framing members have been joined one to another in mutually perpendicular array, as for example a floor joist to a rim joist, through the use of various "L"-, "C"- or "U"-shaped closures, clips or brackets. One of the difficulties attendant the use of such known closures, clips or brackets is the necessity of supporting the joist or other generally horizontal framing member being moved into place for perpendicular attachment to a fixed or permanent like said joist by hand or by mechanical means until secure screw or other fastener attachment between the fixed or permanently placed joist and the joist being moved into perpendicular array thereto can be obtained.
Another disadvantage or, more properly, lack of advantage in the closures, clips and brackets in current use for the attachment of generally C-shaped lightweight metal framing members one to another in mutually perpendicular array is that none of the prior art articles provide protection against joist web crippling by functioning as web stiffeners. Structural framing systems comprising lightweight metallic framing members are not suitable for the carrying of concentrated loads or reactions, or the vectoral components thereof, when such loads or reactions act perpendicular to the longitudinal axis or elongate dimension of the framing member, and also act in the plane of the web of the framing member and further when such loads or reactions force the rotation of the web out of its plane along the bearing length, for such loads or reactions cause respectively, compressive stresses and shear stresses in that web to the point of ultimate structural failure of the web, that is, web crippling. As provided by the American Iron and Steel Institute of Washington, D.C., in its publication Specification for the Design of Cold-Formed Steel Structural Members of Sept. 3, 1980 in Section 3.5 and particularly in sub-Section 3.5.1, it has been determined that neither concentrated loads nor reactions acting perpendicular to the longitudinal axis or elongate dimension of such a structural member and acting in the plane of the web thereof may exceed certain values when the unreinforced flat webs of said structural flexural members have a flat width ratio, h/t, numerically greater than 200, where h is the clear distance between the flanges measured along the plane of the web of that structural member and is given in inches, and where t is the base steel thickness of any element or section, again being given in inches, unless adequate means be provided for the transmission of such concentrated loads or reactions directly from the bearing flange of said generally C-shaped structural member into the web portion of the structural member. Many such means for the transmission of concentrated loads or reactions directly into the web portion of the lightweight metallic structural member are known in the art, and are commonly known as "web stiffeners" for attachment to the web, and provide for the transmission of said loads or reactions from the upper or bearing flange to the lower or non-bearing flange and thus into the web. Such web stiffeners, when properly installed either at the ends of the structural member, or intermediate along the longitudinal axis of that structural member, maximize load bearing capacity in providing reinforcement of the structural under concentrated loads or reactions.
In no device known in the prior art, however, are the capabilities and functions of interconnection of generally C-shaped structural members in mutually perpendicular array and the provision of means for the transmission of concentrated loads or reactions to the web, i.e., web stiffening simultaneously provided.
A further deficiency of the closures, clips and brackets found in the prior art for the attachment of generally C-shaped lightweight metal framing members one to another in perpendicular array is that most such devices require that the fixed or permanently placed joist or other generally horizontal framing member be configured in mutually perpendicular array with other such framing members such that the generally C-shaped configuration face the exterior of that array, making necessary the attachment to that C-shaped configuration a closure to enable that surface to receive collateral finishing materials such as sheathing, stucco, wood or concrete panels, wood or aluminum siding, or composite facing materials.
3. Objects of the Invention
It is accordingly a first object of this invention to provide economic means for the safe and facile interconnection of large or heavy generally C-shaped structural members in mutually perpendicular array, that interconnection to be performed in the field or on the job site without the use of heavy equipment for the placement of said structural members in said array.
It is a further object of this invention to provide web stiffening means to said generally C-shaped structual members in conformity with the standards known in the art as promulgated by the American Iron and Steel Institute for meeting concentrated loads or reactions upon the web of said structural members.
It is a further object of this invention to provide a joist connector and web stiffener which, when used in the construction of horizontal load-bearing systems such as floors or ceilings comprising floor or ceiling joists and rim joists, allows the web of the rim joist to face the exterior, thereby greatly facilitating the attachment of sheathing, facing materials or other collateral materials.
It is therefore a concomitant object of this invention to provide an integral joist connector and web stiffener which can be inserted into the end of a first generally C-shaped structural member, that partial assembly then being inserted between the flanges and adjacent the web of a second like said member, wherein final assembly is effected by rotatably urging the first sub-assembly into register with the flanges and flange return edges of the second said member, thereby providing mutual perpendicularity between each of said generally C-shaped structural members.